1. Field of the Invention
The present invention relates to an image forming apparatus. More particularly, the present invention relates to an image forming apparatus having a print head which is movable so as to prevent a paper jam.
2. Description of the Related Art
An image forming apparatus such as a photo printer employs a thermal transfer method for forming an image. In a thermal transfer method heat is applied to a printing medium such as a thermosensitive paper in order to form an image. An exemplary conventional thermal transfer type image forming apparatus is shown in FIG. 1.
Referring to FIG. 1, a conventional thermal transfer type image forming apparatus comprises a print head 10 having a heater assembly. The heater assembly includes a plurality of heaters (not shown) arranged at predetermined intervals in a row. The conventional thermal transfer type image forming apparatus further includes a platen roller 20 for supporting the printing medium when the print head 10 heats the printing medium and forms an image. The print head 10 is provided with a plurality of driving chips that each control a respective group of heaters from the plurality of heaters. The print head 10 is further provided with a protective coating layer to cover and protect the plurality of driving chips.
The print head 10, prior to picking up the printing medium, is situated to be close to the platen roller 20, as illustrated with a dotted line in FIG. I. When a printing signal is transmitted from a controlling part (not shown), a pickup roller (not shown) picks up the printing medium. The printing medium is then moved by a feed roller 30 so as to be positioned between the platen roller 20 and the print head 10. The print head 10 rotates about a hinge axis 12 in a direction ‘A’ so as to be spaced apart from the platen roller 20 thus allowing the printing medium to enter.
Recesses are formed between respective driving chips and the protective layer. Due to the recesses, the printing medium contacting the protective layer develops vertical stripes that correlate to the recesses. The vertical stripes occur as a result of the heat generated from the driving chips. A cover 14 covering the protective layer is formed to prevent such vertical stripes from being created. The heater assembly heating the printing medium is exposed to the outside. The cover 14 is formed on a portion of the upper side of the print head 10 with a height difference being created between the cover 14 and the heater assembly. Due to the height difference, a front end of the printing medium entering between the platen heater 20 and the print head 10, through the feed roller 30, is caught at an end of the cover 14 thereby causing a paper jam.
Accordingly, there is a need for an improved image forming apparatus having a print head which is operable so as to prevent a paper jam.